{ "id": "1308.6812", "version": "v1", "published": "2013-08-30T17:58:52.000Z", "updated": "2013-08-30T17:58:52.000Z", "title": "A classification of nilpotent 3-BCI groups", "authors": [ "Hiroki Koike", "István Kovács" ], "categories": [ "math.GR", "math.CO" ], "abstract": "Given a finite group $G$ and a subset $S\\subseteq G,$ the bi-Cayley graph $\\bcay(G,S)$ is the graph whose vertex set is $G \\times \\{0,1\\}$ and edge set is $\\{\\{(x,0),(s x,1)\\} : x \\in G, s\\in S \\}$. A bi-Cayley graph $\\bcay(G,S)$ is called a BCI-graph if for any bi-Cayley graph $\\bcay(G,T),$ $\\bcay(G,S) \\cong \\bcay(G,T)$ implies that $T = g S^\\alpha$ for some $g \\in G$ and $\\alpha \\in \\aut(G)$. A group $G$ is called an $m$-BCI-group if all bi-Cayley graphs of $G$ of valency at most $m$ are BCI-graphs.In this paper we prove that, a finite nilpotent group is a 3-BCI-group if and only if it is in the form $U \\times V,$ where $U$ is a homocyclic group of odd order, and $V$ is trivial or one of the groups $\\Z_{2^r},$ $\\Z_2^r$ and $\\Q_8$.", "revisions": [ { "version": "v1", "updated": "2013-08-30T17:58:52.000Z" } ], "analyses": { "subjects": [ "05C25" ], "keywords": [ "bi-cayley graph", "classification", "finite nilpotent group", "finite group", "homocyclic group" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2013arXiv1308.6812K" } } }